Heat dissipation device and a method for manufacturing same

ABSTRACT

A heat dissipation device includes a first copper sheet and a second copper sheet. The first copper sheet includes a number of first recesses and the second copper sheet includes a number of corresponding second recesses. The second copper sheet is fixed on the first copper sheet and an airtight receiving cavity is formed by each first recess and each the second recess, a working fluid in the airtight receiving cavity carries unwanted heat away.

FIELD

The subject matter herein generally relates to temperature control.

BACKGROUND

Since a high-power electronic device generates a large amount of heat during operation, the performance and lifetime of the electronic device is lowered if the heat cannot be dissipated in time.

BRIEF DESCRIPTION OF THE DRAWINGS

Implementations of the present technology will now be described, by way of example only, with reference to the attached figures.

FIG. 1 is a diagrammatic view of a heat dissipation device comprising a first copper sheet in accordance with a first embodiment.

FIG. 2 is a diagrammatic view of the first copper sheet of FIG. 1.

FIG. 3 is a cross sectional view taken along line III-III of the first copper sheet of FIG. 2.

FIG. 4 is a diagrammatic view showing the heat dissipation device used with an electronic device.

FIG. 5 illustrates a flowchart of a method for manufacturing the heat dissipation device of FIG. 1.

FIG. 6 illustrates a diagrammatic view of a first copper sheet and a second copper sheet provided for manufacturing the heat dissipation device.

FIG. 7 is a diagrammatic view of an adhesive on the first copper sheet in FIG. 6.

FIG. 8 is a diagrammatic view of a working fluid received in the first copper sheet.

FIG. 9 is a diagrammatic view of the second copper sheet fixed with the first copper sheet.

DETAILED DESCRIPTION

It will be appreciated that for simplicity and clarity of illustration, where appropriate, reference numerals have been repeated among the different figures to indicate corresponding or analogous elements. In addition, numerous specific details are set forth in order to provide a thorough understanding of the embodiments described herein. However, it will be understood by those of ordinary skill in the art that the embodiments described herein can be practiced without these specific details. In other instances, methods, procedures, and components have not been described in detail so as not to obscure the related relevant feature being described. Also, the description is not to be considered as limiting the scope of the embodiments described herein. The drawings are not necessarily to scale and the proportions of certain parts have been exaggerated to better illustrate details and features of the present disclosure.

Several definitions that apply throughout this disclosure will now be presented.

The term “substantially” is defined to be essentially conforming to the particular dimension, shape, or other feature that the term modifies, such that the component need not be exact. For example, “substantially cylindrical” means that the object resembles a cylinder, but can have one or more deviations from a true cylinder. The term “comprising,” when utilized, means “including, but not necessarily limited to”; it specifically indicates open-ended inclusion or membership in the so-described combination, group, series and the like. The references “a plurality of” and “a number of” mean “at least two.”

The present disclosure is described in relation to a heat dissipation device. The heat dissipation device includes a first copper sheet and a second copper sheet. The first copper sheet includes a number of first recesses; the second copper sheet includes a number of second recesses.

The second recesses correspond with the first recesses and the second copper sheet is fixed on the first copper sheet. An airtight receiving cavity is formed by each first recess and second recess together and a working fluid is received in the airtight receiving cavity.

FIG. 1 illustrates a heat dissipation device 100 according to one embodiment. The heat dissipation device 100 includes a first copper sheet 10, a second copper sheet 40, and an adhesive 20 configured for fixing the first copper sheet 10 and the second copper sheet 40 together. A number of airtight receiving cavities 404 are formed by the first copper sheet 10 and the second copper sheet 40 and a working fluid 30 is received in each of the airtight receiving cavities 404.

The first copper sheet 10 includes a first surface 101. The first surface 101 defines a number of first recesses 102 which are randomly distributed on the first surface 101, and the first recesses 102 are substantially strip-shaped, as shown in FIG. 2. A cross section of the first and second recesses 102 and 402 is an arc or a semicircle, as shown in FIG. 3. A depth of each first recess 102 is smaller than a thickness of the first copper sheet 10. A thickness of each first copper sheet 10 and second copper 40 sheet is about 140 um.

The second copper sheet 40 has substantially the same structure and shape as the first copper sheet 40. The second copper sheet 40 includes a second surface 401. The second surface 401 defines a number of second recesses 402 corresponding with the first recesses 102. A depth of each second recess 402 is smaller than a thickness of the second copper sheet 40. The second recesses 402 and the first recesses 102 have the same shape and size. A number of first ribs 104 are formed between each two adjacent first recesses 102. A number of second ribs 404 are formed between each two adjacent second recesses 402, the first ribs 104 correspond locationally with the second ribs 404.

The adhesive 20 is arranged on the ribs 104 and the first copper sheet 10 and the second copper sheet 40 are fixed by the adhesive 20. In the illustrated embodiment, the adhesive 20 is low temperature solder paste, a melting point of the low temperature solder paste is about 139° C. or less. The first recesses 102 are in communication with the second recesses 402, each first recess 102 and each second recess 402 together form a receiving cavity 404, and the adhesive 20 is on a part of an inner wall of the receiving cavity 404, the adhesive 20 is configured for accelerating cooling the working fluid 30.

The working fluid 30 is received in each receiving cavity 404. The working fluid 30 can be selected from the group comprising water, methanol, ethanol, acetone, ammonia, paraffin, oil, and chlorofluorocarbons at least. In the illustrated embodiment, the working fluid 30 is water. A heat capacity of water is about 4.2×10³J/(kg.), which is larger than a heat capacity of steel sheeting.

FIG. 4 shows the heat dissipation device 100 being used with a heat generating member 60. The heat dissipation device 100 is very thin and fixed with a heat generating member 60 of an electronic device using adhesive (not shown). In this embodiment, the heat generating member 60 is a CPU but is not limited to CPU only. The generating member 60 is fixed on a printed circuit board 50 via solder ball 62. Heat generated by the heat generating member 60 is transferred and gathered at bottom of the first copper sheet 10, and the heat is absorbed by water 30 in the receiving cavity 404 and diffused through the first copper sheet 10 and the second copper sheet 40 during the heat transfer. The water 30 is vaporized, when water vapour is moved to an inner wall of the second recess 402, it condenses into small water droplets which attach to the inner wall of the receiving cavity 404. Finally the small droplets will flow into the first recess 102 again in a continuous process, so heat from the heat generating member 60 of the electronic device is dissipated.

FIG. 5 illustrates a flowchart in accordance with an example embodiment. The example method 200 for manufacturing the heat dissipation device 100 (shown in FIG. 1) is provided by way of an example, as there are a variety of ways to carry out the method. Additionally, the illustrated order of blocks is by example only and the order of the blocks can change. The method 200 can begin at block 201.

At block 201, a first copper base 15, and a second copper base 25 are provided, as shown in FIG. 6. The first copper base 15 includes a first surface 101, the second copper base 25 includes a second surface 201 facing the first surface 101. A thickness of the first copper base 15 is the same as that of the second copper base 25, being about 140 um.

At block 202, the first surface 101 is processed to form a number of first recesses 102, and at the same time, a number of ribs 104 are formed between each two adjacent first recesses 102. The second surface 401 is processed to form a number of second recesses 402, the second recesses 402 and the first recesses 102 have the same shape and size Thereby, the first copper sheet 10 and the second copper sheet 20 are obtained. A depth of each first recess 102 is smaller than a thickness of the first copper sheet 10. A depth of each second recess 402 is smaller than a thickness of the second copper sheet 40. In this embodiment, the first and second recesses 102 and 402 are formed using a laser beam and a cross section of the first and second recesses 102 and 402 is an arc or a semicircle, as shown in FIG. 3.

At block 203, an adhesive 20 is provided on the ribs 104 of the first copper sheet 10, as shown in FIG. 7. A melting point of the adhesive 20 is about 139 degrees or less, but higher than a boiling point of water. That is to say, when water is used for absorbing heat, the adhesive 20 is not influenced by boiling water.

The adhesive 20 is mainly comprised of molten resin material doped with metal particles. The metal particle is selected from a group comprising tin, bismuth, and any combination thereof. A diameter of the metal particle is in the range from about 25 um to 45 um. A weight ratio of tin in the adhesive 20 is in the range from about 37% to 38%. A weight ratio of bismuth in the adhesive 20 is in the range from about 51% to 52%. A weight ratio of molten resin in the adhesive 20 is in the range from about 4% to 6%. In the illustrated embodiment, the resin is C₁₉H₂₉COOH and the adhesive 20 also comprises solvent C₁₀H₂₀O₃, which is active agent C₄H₆O₄, and an anti-oxidant: C₇H₇N₃ is configured for avoiding oxidation of the metal particles. The weight ratio of the solvent, active agent, and antioxidant are respectively 1.0% ˜3.0%, 0.1% ˜0.3%, 0.05% ˜0.06%. The proportion of the adhesive 20 as specified above is able to obtain a better adhesion and have less susceptibility to water.

At block 204, a working fluid 30 is provided in the first recesses 102, as shown in FIG. 8.

At block 205, the second copper sheet 40 is pressed on the adhesive 20 and the second copper sheet 40 is fixed with the first copper sheet by the adhesive 20, as shown in FIG. 9, each of the first recesses 102 are in communication with each of the second recesses 402 and each of the first recess 102 and the second recesses 402 together form an airtight receiving cavity 404. When the adhesive 20 is solidified a heat dissipation device 100 is obtained.

The embodiments shown and described above are only examples. Therefore, many such details are neither shown nor described. Even though numerous characteristics and advantages of the present technology have been set forth in the foregoing description, together with details of the structure and function of the present disclosure, the disclosure is illustrative only, and changes may be made in the detail, including in matters of shape, size, and arrangement of the parts within the principles of the present disclosure, up to and including the full extent established by the broad general meaning of the terms used in the claims. It will therefore be appreciated that the embodiments described above may be modified within the scope of the claims. 

What is claimed is:
 1. A heat dissipation device comprising: a first copper sheet comprising a plurality of first recesses; a second copper sheet comprising a plurality of second recesses, the second recesses corresponding with the first recesses, the second copper sheet being fixed on the first copper sheet and each the second recesses facing the corresponding first recesses, an airtight receiving cavity being formed by each of the first recesses and the second recesses, the second copper sheet being fixed on the first copper sheet with adhesive, the adhesive forms a part of an inner wall of the airtight receiving cavity; and a working fluid received in the airtight receiving cavity.
 2. The heat dissipation device of claim 1, wherein the first copper sheet comprises a first surface, the second copper sheet comprises a second surface facing the first surface, the first recesses are randomly distributed on the first surface.
 3. The heat dissipation device of claim 2, wherein the first copper sheet comprises a plurality of first ribs, the first ribs are formed between each two adjacent first recesses, the second copper sheet comprises a plurality of second ribs, the second ribs are formed between each two adjacent second recesses, the first ribs are corresponding with the second ribs.
 4. The heat dissipation device of claim 1, wherein the adhesive is low temperature solder paste.
 5. The heat dissipation device of claim 4, wherein the adhesive comprises a molten resin material doped with metal particles, the metal particle is selected from the group comprising tin, bismuth and any combination thereof.
 6. The heat dissipation device of claim 5, wherein a weight ratio of tin in the adhesive is in the range from about 37% to about 38%, a weight ratio of bismuth in the adhesive is in the range from about 51% to about 52%, and a weight ratio of molten resin in the adhesive is in the range from about 4% to about 6%.
 7. The heat dissipation device of claim 3, wherein the adhesive is sandwiched between the first ribs and the second ribs.
 8. The heat dissipation device of claim 1, wherein a cross section of the first and second recesses is an arc or a semi circle.
 9. A heat dissipation device, comprising: a first copper sheet comprising a plurality of first recesses; a second copper sheet comprising a plurality of second recesses, the second recesses being corresponding with the first recesses, the second copper sheet being fixed on the first copper sheet such that each of the second recesses mate with the corresponding first recesses to define a plurality of an airtight receiving cavities being formed by each the first recess and the second recess; and a working fluid in each of the airtight receiving cavities; wherein the first and second copper sheets are configured to transmit external heat from an outer surface toward the working fluid, thereby providing a heat sink.
 10. A method for manufacturing the heat dissipation device, the method comprising: providing a first copper base and a second copper base, the first copper base comprises a first surface, the second copper base comprises a second surface facing toward the first surface; processing the first surface to form a number of first recess and a number of ribs between each two adjacent first recesses, processing the second surface to form a number of second recesses, the second recesses and the first recesses have the same shape and size; providing an adhesive on the ribs of the first copper sheet; providing a working fluid in the first recesses of the first copper sheet; pressing the second copper sheet on the adhesive, and the second copper sheet is fixed with the first copper sheet by the adhesive, each the first recesses are in communication with the second recesses, each of the first recesses and the second recesses together form an airtight receiving cavity; solidifying the adhesive.
 11. The method of claim 9, wherein the a depth of each first recesses is smaller than a thickness of the first copper sheet, a depth of each second recesses is smaller than a thickness of the second copper sheet.
 12. The method of claim 10, wherein the adhesive is low temperature solder paste.
 13. The method of claim 12, wherein the adhesive comprises of molten resin material doped with metal particles, the metal particle is selected from the group comprising tin, bismuth and any combination thereof.
 14. The method of claim 13, wherein a weight ratio of tin in the adhesive is in the range from about 37% to about 38%, a weight ratio of bismuth in the adhesive is in the range from about 51% to about 52%, and a weight ratio of molten resin in the adhesive is in the range from about 4% to about 6%.
 15. The method of claim 13, wherein the working fluid at least is able to select from the group comprising water, methanol, ethanol, acetone, ammonia, paraffin, oil, and chlorofluorocarbons. 